'\" et
.TH MBSRTOWCS "3P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\"
.SH PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
.\"
.SH NAME
mbsnrtowcs, mbsrtowcs
\(em convert a character string to a wide-character string (restartable)
.SH SYNOPSIS
.LP
.nf
#include <wchar.h>
.P
size_t mbsnrtowcs(wchar_t *restrict \fIdst\fP, const char **restrict \fIsrc\fP,
    size_t \fInmc\fP, size_t \fIlen\fP, mbstate_t *restrict \fIps\fP);
size_t mbsrtowcs(wchar_t *restrict \fIdst\fP, const char **restrict \fIsrc\fP,
    size_t \fIlen\fP, mbstate_t *restrict \fIps\fP);
.fi
.SH DESCRIPTION
For
\fImbsrtowcs\fR():
The functionality described on this reference page is aligned with the
ISO\ C standard. Any conflict between the requirements described here and the
ISO\ C standard is unintentional. This volume of POSIX.1\(hy2017 defers to the ISO\ C standard.
.P
The
\fImbsrtowcs\fR()
function shall convert a sequence of characters, beginning in the
conversion state described by the object pointed to by
.IR ps ,
from the array indirectly pointed to by
.IR src
into a sequence of corresponding wide characters. If
.IR dst
is not a null pointer, the converted characters shall be stored into
the array pointed to by
.IR dst .
Conversion continues up to and including a terminating null character,
which shall also be stored. Conversion shall stop early in either of
the following cases:
.IP " *" 4
A sequence of bytes is encountered that does not form a valid character.
.IP " *" 4
.IR len
codes have been stored into the array pointed to by
.IR dst
(and
.IR dst
is not a null pointer).
.P
Each conversion shall take place as if by a call to the
\fImbrtowc\fR()
function.
.P
If
.IR dst
is not a null pointer, the pointer object pointed to by
.IR src
shall be assigned either a null pointer (if conversion stopped due to
reaching a terminating null character) or the address just past the
last character converted (if any). If conversion stopped due to
reaching a terminating null character, and if
.IR dst
is not a null pointer, the resulting state described shall be the
initial conversion state.
.P
If
.IR ps
is a null pointer, the
\fImbsrtowcs\fR()
function shall use its own internal
.BR mbstate_t
object, which is initialized at program start-up to the initial
conversion state. Otherwise, the
.BR mbstate_t
object pointed to by
.IR ps
shall be used to completely describe the current conversion state of
the associated character sequence.
.P
The
\fImbsnrtowcs\fR()
function shall be equivalent to the
\fImbsrtowcs\fR()
function, except that the conversion of characters indirectly
pointed to by
.IR src
is limited to at most
.IR nmc
bytes (the size of the input buffer), and under conditions where
\fImbsrtowcs\fR()
would assign the address just past the last character converted (if any)
to the pointer object pointed to by
.IR src ,
\fImbsnrtowcs\fR()
shall instead assign the address just past the last byte processed
(if any) to that pointer object. If the input buffer ends with an
incomplete character, it is unspecified whether conversion stops at
the end of the previous character (if any), or at the end of the input
buffer. In the latter case, a subsequent call to
\fImbsnrtowcs\fR()
with an input buffer that starts with the remainder of the incomplete
character shall correctly complete the conversion of that character.
.P
The behavior of these functions shall be affected by the
.IR LC_CTYPE
category of the current locale.
.P
The implementation shall behave as if no function defined in this volume of POSIX.1\(hy2017
calls these functions.
.P
The
\fImbsnrtowcs\fR()
and
\fImbsrtowcs\fR()
functions need not be thread-safe if called with a NULL
.IR ps
argument.
.P
The
\fImbsrtowcs\fR()
function shall not change the setting of
.IR errno
if successful.
.SH "RETURN VALUE"
If the input conversion encounters a sequence of bytes that do not form
a valid character, an encoding error occurs. In this case, these
functions shall store the value of the macro
.BR [EILSEQ] 
in
.IR errno
and shall return (\fBsize_t\fP)\-1; the conversion state is undefined.
Otherwise, these functions shall return the number of characters
successfully converted, not including the terminating null (if any).
.SH ERRORS
These functions shall fail if:
.TP
.BR EILSEQ
An invalid character sequence is detected.
In the POSIX locale an
.BR [EILSEQ] 
error cannot occur since all byte values are valid characters.
.P
These functions may fail if:
.TP
.BR EINVAL
.IR ps
points to an object that contains an invalid conversion state.
.LP
.IR "The following sections are informative."
.SH EXAMPLES
None.
.SH "APPLICATION USAGE"
None.
.SH RATIONALE
None.
.SH "FUTURE DIRECTIONS"
A future version may require that when the input buffer ends with
an incomplete character, conversion stops at the end of the input buffer.
.SH "SEE ALSO"
.IR "\fIiconv\fR\^(\|)",
.IR "\fImbrtowc\fR\^(\|)",
.IR "\fImbsinit\fR\^(\|)"
.P
The Base Definitions volume of POSIX.1\(hy2017,
.IR "\fB<wchar.h>\fP"
.\"
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1-2017, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition,
Copyright (C) 2018 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
In the event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
.PP
Any typographical or formatting errors that appear
in this page are most likely
to have been introduced during the conversion of the source files to
man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
